Phenol induced growth in Triton X-100 micelles: Effect of pH and phenols’ hydrophobicity

Cloud point, viscosity and dynamic light scattering data on aqueous micellar solutions of a nonionic surfactant Triton X-100 in the presence of several phenolic solutes are reported. These additives alter the surfactantʹs solution behavior depending on their hydrophobicity and pH of the solution. α-Naphthol, p-cresol and phenol induced micellar growth whereas more hydrophilic catechol, quinol, resorcinol did not show any significant change in micelle size. Increase in p-cresol concentration, decrease in pH and increase in temperature favored micelle growth. NMR results show that at lower concentration (10 mM) p-cresol resides in the shell region while at higher concentration (40 mM) both in shell region and core/shell interface. Quinol resides at micelle–water interface even at high concentration (40 mM).